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authorJeff Dike <jdike@addtoit.com>2005-09-03 15:57:36 -0700
committerLinus Torvalds <torvalds@evo.osdl.org>2005-09-05 00:06:22 -0700
commitc56004901fa5dcf55f92318f192ab3c0e87db2d1 (patch)
treeac53ded16ab9886ce05d4b2d424dfed80dce9e57 /arch/um/sys-x86_64/stub.S
parent77fa5adcda6d686d2f45a2b55dcb9a03e7d33fa1 (diff)
downloadop-kernel-dev-c56004901fa5dcf55f92318f192ab3c0e87db2d1.zip
op-kernel-dev-c56004901fa5dcf55f92318f192ab3c0e87db2d1.tar.gz
[PATCH] uml: TLB operation batching
This adds VM op batching to skas0. Rather than having a context switch to and from the userspace stub for each address space change, we write a number of operations to the stub data page and invoke a different stub which loops over them and executes them all in one go. The operations are stored as [ system call number, arg1, arg2, ... ] tuples. The set is terminated by a system call number of 0. Single operations, i.e. page faults, are handled in the old way, since that is slightly more efficient. For a kernel build, a minority (~1/4) of the operations are part of a set. These sets averaged ~100 in length, so for this quarter, the context switching overhead is greatly reduced. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/um/sys-x86_64/stub.S')
-rw-r--r--arch/um/sys-x86_64/stub.S21
1 files changed, 21 insertions, 0 deletions
diff --git a/arch/um/sys-x86_64/stub.S b/arch/um/sys-x86_64/stub.S
index 31c1492..957f2ef 100644
--- a/arch/um/sys-x86_64/stub.S
+++ b/arch/um/sys-x86_64/stub.S
@@ -13,3 +13,24 @@ syscall_stub:
or %rcx, %rbx
movq %rax, (%rbx)
int3
+
+ .globl batch_syscall_stub
+batch_syscall_stub:
+ movq $(UML_CONFIG_STUB_DATA >> 32), %rbx
+ salq $32, %rbx
+ movq $(UML_CONFIG_STUB_DATA & 0xffffffff), %rcx
+ or %rcx, %rbx
+ movq %rbx, %rsp
+again: pop %rax
+ cmpq $0, %rax
+jz done
+ pop %rdi
+ pop %rsi
+ pop %rdx
+ pop %r10
+ pop %r8
+ pop %r9
+ syscall
+ mov %rax, (%rbx)
+ jmp again
+done: int3
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